1. Field of the Invention
The present disclosure generally relates to semiconductor devices, and more particularly, to semiconductor optical modulators.
2. Background Information
Optical waves have carrier frequencies on the order of 1014 Hz and hence can be modulated at frequencies higher than radio-frequency waves and microwaves. Such high-frequency modulation allows an optical wave to have a high bandwidth for transmitting information such as an optic fiber link in a communication system. Optical transmission also offers immunity to electromagnetic interference, cross talk and other adverse effects suffered by electrical transmission. Further, information carried by an optical wave may be processed optically to achieve a high processing speed and parallel processing in certain applications, such as imaging through a lens system. Moreover, optical materials may be used for high-density data storage such as holographic memories. Therefore, data transmission and processing through optical waves can provide significant advantages in various aspects over their electronic counterparts.
However, current optical systems and devices have limitations. This is in part because many optical technologies are still in their infancy and in part because the inherent characteristics of the optical waves and respective devices restrict their use in many applications. As a result, there has been an effort in integrating certain optical systems and devices with electronic systems and devices to form hybrid optoelectronic systems and devices so as to take the advantages of both optical and electronic sides and to avoid their respective shortcomings. For example, electronic processors may be used to process the information in the electrical domain. The electronic data is then converted into optical signals for transmission over a high-speed optical link.
One important area for many hybrid optoelectronic systems or devices is in electronic-to-optical interfacing devices that convert electronic signals into optical signals. This conversion can be achieved by using electrically controlled optical modulators to modulate at least one parameter of an optical wave, such as the amplitude, phase, frequency, or a combination of these parameters.
Optical signal switches may also be based on optical modulators. Since many electronic circuits are integrated on silicon wafers, it is often desirable to use photosensitive semiconductors to construct the optical modulators in compact form and integrate them onto silicon wafers.
Many highly photosensitive semiconductor materials are compounds made from III-V elements, such as GaAs and InP. It can be technically difficult to grow these materials on a silicon wafer due to their lattice mismatch. One way to integrate discrete components of different semiconductor materials uses an interconnect such as an indium bump. Such integration can be limited in several aspects. It adds extra size. It can also have an increased parasitic effect.
An apparatus and method for a radiation beam modulator are disclosed. In one embodiment, a disclosed semiconductor device includes a substrate of a semiconductor material configured to have an integrated circuit element that defines a first area and a second area that are at different electrical potentials. A superlattice structure is formed in the integrated circuit element relative to the first and second areas to have alternating layers formed of the semiconductor material and insulator layers formed of another material. The semiconductor layers and insulator layers are configured to cause direct bandgap absorption of radiation energy in the semiconductor layers to modulate a radiation beam that passes through the superlattice structure in response to a potential difference between the first and second areas. Additional features and benefits of the present invention will become apparent from the detailed description, figures and claims set forth below.